As far as NFTs are concerned, the existence of multiple incompatible blockchains is indistinguishable from what would be considered a network partition within a single blockchain for cryptocurrency.
@stagas:
> Can't they have a public personal ledger somewhere for people to audit?
Then you need to coordinate on a common authority to rely upon for the timestamping. Blockchain's whole purpose is to eliminate this dependency.
Without third-party timestamping or blockchain, the same token can be sold to multiple buyers, and nothing can be used to determine which buyer is the first ("real") buyer.
This is the whole reason blockchain was invented. It wasn't possible to do it at all before that.
As it stands this isn't very valuable yet but in my mind an important milestone.
Blockchains simply reduce the power and trust required in the third party by offering a different set of tradeoffs.
I haven't puzzled it though but intuitively it feels like you wouldn't be able to achieve the "same validity" (aka you'd have a weaker set of guarentees) without the liveness of a blockchain like system. Whether you agree with what threshold of validity is acceptable is a different matter.